/* JQuery文件上传组件 */
jQuery.extend({
	createUploadIframe:function(id, uri) {
		// create frame
		var frameId = 'jUploadFrame' + id;
		if (window.ActiveXObject) {
			var io = document.createElement('<iframe id="' + frameId + '" name="' + frameId + '" />');
			if (typeof uri == 'boolean') {
				io.src = 'javascript:false';
			} else if (typeof uri == 'string') {
				io.src = uri;
			}
		} else {
			var io = document.createElement('iframe');
			io.id = frameId;
			io.name = frameId;
		}
		io.style.position = 'absolute';
		io.style.top = '-1000px';
		io.style.left = '-1000px';

		document.body.appendChild(io);
		return io;
	},

	createUploadForm:function(id, fileElementId) {
		// create form	
		var formId = 'jUploadForm' + id;
		var fileId = 'jUploadFile' + id;
		var form = $('<form  action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>');	
		var oldElement = $('#' + fileElementId);
		var newElement = $(oldElement).clone();
		$(oldElement).attr('id', fileId);
		$(oldElement).before(newElement);
		$(oldElement).appendTo(form);
		// set attributes
		$(form).css('position', 'absolute');
		$(form).css('top', '-1200px');
		$(form).css('left', '-1200px');
		$(form).appendTo('body');
		return form;
	},

	ajaxFileUpload:function(s) {
		// TODO introduce global settings, allowing the client to modify them for all requests, not only timeout
		s = jQuery.extend({}, jQuery.ajaxSettings, s);
		var id = new Date().getTime();
		var form = jQuery.createUploadForm(id, s.fileElementId);
		var io = jQuery.createUploadIframe(id, s.secureuri);
		var frameId = 'jUploadFrame' + id;
		var formId = 'jUploadForm' + id;
		// Watch for a new set of requests
		if ( s.global && ! jQuery.active++ ) {
			jQuery.event.trigger( "ajaxStart" );
		}
		var requestDone = false;
		// Create the request object
		var xml = {};
		if ( s.global )
			jQuery.event.trigger("ajaxSend", [xml, s]);
		// Wait for a response to come back
		var uploadCallback = function(isTimeout) {
			var io = document.getElementById(frameId);
			try {
				if(io.contentWindow) {
					try {xml.responseText = io.contentWindow.document.body?io.contentWindow.document.body.innerHTML:null;} catch (e) {}
					try {xml.responseXML = io.contentWindow.document.XMLDocument?io.contentWindow.document.XMLDocument:io.contentWindow.document;} catch (e) {}
				} else if(io.contentDocument) {
					try {xml.responseText = io.contentDocument.document.body?io.contentDocument.document.body.innerHTML:null;} catch (e) {}
					try {xml.responseXML = io.contentDocument.document.XMLDocument?io.contentDocument.document.XMLDocument:io.contentDocument.document;} catch (e) {}
				}
			} catch(e) {
				jQuery.handleError(s, xml, null, e);
			}
			if ( xml || isTimeout == "timeout") {
				requestDone = true;
				var status;
				try {
					status = isTimeout != "timeout" ? "success" : "error";
					// Make sure that the request was successful or notmodified
					if ( status != "error" ) {
						// process the data (runs the xml through httpData regardless of callback)
						var data = jQuery.uploadHttpData( xml, s.dataType );
						// If a local callback was specified, fire it and pass it the data
						if ( s.success )
							s.success( data, status );
						// Fire the global callback
						if( s.global )
							jQuery.event.trigger( "ajaxSuccess", [xml, s] );
					} else {
						jQuery.handleError(s, xml, status);
					}
				} catch(e) {
					status = "error";
					jQuery.handleError(s, xml, status, e);
				}
				// The request was completed
				if( s.global )
					jQuery.event.trigger( "ajaxComplete", [xml, s] );

				// Handle the global AJAX counter
				if ( s.global && ! --jQuery.active )
					jQuery.event.trigger( "ajaxStop" );

				// Process result
				if ( s.complete )
					s.complete(xml, status);

				jQuery(io).unbind()

				setTimeout(function() {
					try {
						$(io).remove();
						$(form).remove();	
					} catch(e) {
						jQuery.handleError(s, xml, null, e);
					}}, 100);

				xml = null;
			}
		}
		// Timeout checker
		if ( s.timeout > 0 ) {
			setTimeout(function(){
				// Check to see if the request is still happening
				if( !requestDone ) uploadCallback( "timeout" );
				}, s.timeout);
		}
		try {
			// var io = $('#' + frameId);
			var form = $('#' + formId);
			$(form).attr('action', s.url);
			$(form).attr('method', 'POST');
			$(form).attr('target', frameId);
			for (key in s.postdata) {
				var input = $("<input type='hidden' />");
				input.attr("name", key);
				input.attr("value", s.postdata[key]);
				input.appendTo(form);
			}
			if(form.encoding) {
				form.encoding = 'multipart/form-data';
			} else {
				form.enctype = 'multipart/form-data';
			}
			$(form).submit();
		} catch(e) {
			jQuery.handleError(s, xml, null, e);
		}
		if(window.attachEvent){
			document.getElementById(frameId).attachEvent('onload', uploadCallback);
		} else{
			document.getElementById(frameId).addEventListener('load', uploadCallback, false);
		}
		return {abort: function () {}};
	},

	uploadHttpData: function( r, type ) {
		var data = !type;
		data = type == "xml" || data ? r.responseXML : r.responseText;
		// If the type is "script", eval it in global context
		if ( type == "script" )
			jQuery.globalEval( data );
		// Get the JavaScript object, if JSON is used.
		if ( type == "json" )
			eval( "data = " + data );
		// evaluate scripts within html
		if ( type == "html" )
			jQuery("<div>").html(data).evalScripts();
		//alert($('param', data).each(function(){alert($(this).attr('value'));}));
		return data;
	}
});
